Amplification of c-erbB-2 oncoprotein has been described in 10-35% of primary breast cancers. Breast tumors with immunohistochemical overexpression of c-erbB-2 protein seem to be more aggressive. We evaluated the impact of c-erbB-2 overexpression on clinical and histopathological parameters of patients with breast cancer.

C-erbB-2 overexpression was seen in 72 out of 417 (17%) of primary breast tumors. Patients with positive immunohistochemistry (IHC) for c-erbB-2 were significantly younger (P = 0.015), on average. The number of involved lymph nodes was higher in patients with positive IHC (P = 0.014). Nearly all IHC positive tumors (98.6%) were invasive ductal carcinomas, whereas all but one lobular carcinoma were negative. Tumors with negative IHC more often demonstrated positive estrogen (P = 0.001) and proges-terone (P = 0.001) expression than did patients with positive IHC. There was a significant relation of c-erbB-2 IHC and nuclear grading, Ki67 and p53. No association was found with menopausal status, tumor size, T-staging and presence of metastases.

(1) Overexpression of c-erbB-2 oncoprotein in primary breast cancer tumors may be an indicator of the extent of lymph node metastases in patients. (2) Lobular carcinomas represent a defined subtype of breast carcinomas.